Fabrics obtained by weaving warps and wefts have conventionally been used widely as an industrial fabric. They are, for example, used in various fields including papermaking wires, conveyor belts and filter cloths and are required to have fabric properties suited for the intended use or using environment. Of such fabrics, a papermaking wire used in a papermaking step for removing water from raw materials by making use of the network of the fabric must satisfy a severe demand. There is therefore a demand for the development of fabrics which do not transfer a wire mark of the fabric and therefore have excellent surface property, have enough rigidity and therefore are usable desirably even under severe environments, or are capable of maintaining conditions necessary for making good paper for a prolonged period of time. In addition, fiber supporting property, improvement in a papermaking yield, good water drainage property, wear resistance, dimensional stability and running stability are demanded. In recent years, owing to the speed-up of a papermaking machine, requirements for papermaking wires become severe further.
Since most of the demands for industrial fabrics and solutions thereof can be understood if papermaking fabrics on which the most severe demand is imposed among industrial fabrics will be described, the present invention will hereinafter be described by use of the papermaking fabric as a representative example.
In the paper making machine, an increase in paper making speed inevitably raises dehydration speed so that dehydration power must be reinforced. Examples of the fabric with good dehydration property include two-layer fabric having a dehydration hole penetrating from the upper surface side toward the lower surface side of the fabric. Particularly, a two-layer fabric using a warp binding yarn which is woven with an upper surface side weft and a lower surface side weft to constitute the upper surface side surface design and the lower surface side surface design is developed with a view to satisfying the surface property, fiber supporting property and dehydration property which a papermaking fabric is required to have. A two-layer fabric using a warp binding yarn is described in Japanese Patent Laid-Open No. 2004-36052. In the fabric disclosed in the above-described invention, a warp functions as a binding yarn for weaving the upper surface side layer with the lower surface side layer. A pair of two warp binding yarns simultaneously and mutually complement a portion of the upper surface side surface design and a portion of the lower surface side surface design to form each surface design so that the fabric has excellent surface property and binding strength. The lower surface side design of the fabric in Examples 1 to 3 of Japanese Patent Laid-Open No. 2004-36052 is however a ribbed design in which two lower surface side warps are arranged in parallel while having the same design and a crimp of a lower surface side weft corresponds to only two warps so that the fabric has poor wear resistance.